Priscilla Lynch presents a round-up of the latest impactful international studies on depression
Allergies increase risk of depression and anxiety
A new study of almost 200,000 people has confirmed that having an allergic disease leads to an increased risk of developing depression and anxiety.
The results of the Taiwan study, published in Frontiers in Psychiatry, found a link between allergic rhinitis (hay fever), asthma and atopic dermatitis (eczema), the so-called ‘three As’, with psychiatric disease.
The cohort study used the database of the Taiwan National Health Insurance (NHI) Programme. A total of 186,588 enrolled patients, with 46,647 study subjects who had suffered from allergic diseases, and 139,941 controls matched for sex and age, from the Longitudinal Health Insurance Dataset of 2000-2015, were selected from a sub-dataset of the National Health Insurance Research Database (NHIRD).
The risk of allergic diseases being associated with the risk of developing psychiatric disorders was analysed during the 15 years of follow-up.
Of the study subjects, 5,038 (10.8 per cent) developed psychiatric disorders when compared to 9,376 (6.7 per cent) in the control group.
Atopic dermatitis alone, and allergic rhinitis and atopic dermatitis were associated with a lower risk of psychiatric disorders, but all the other four groups, such as bronchial asthma alone, allergic rhinitis alone, bronchial asthma and allergic rhinitis, bronchial asthma and atopic dermatitis, and the combination of all these three allergic diseases were associated with a higher risk of psychiatric disorders.
Allergic diseases are therefore associated with a 1.66-fold increased hazard of psychiatric disorders in Taiwan, the study concluded.
The researchers believe inflammation caused by the allergies may also be increasing the likelihood of psychiatric conditions and that the stress of coping with an allergy may also explain the link.
“As a clinician, I observed that some patients with the three As appeared to suffer emotionally. We would like to let clinicians who care for patients with allergic diseases know that their risk for psychiatric diseases may be higher,” said Dr Nian-Sheng Tzeng, who led the study.
“Assessing their emotional condition and monitoring their mental health could help to avoid later psychiatric problems.”
Depression study pinpoints genes that may trigger the condition
UK researchers have identified a number of genes that may be involved in the development of depression.
The team carried out DNA screening of 322,580 people from the UK Biobank for three depression-related phenotypes: Broad depression, probable major depressive disorder (MDD), and International Classification of Diseases (ICD- 9 or ICD-10)-coded MDD phenotypes, and identified 17 risk variants, (independent loci) that were significantly associated across the three phenotypes.
They then confirmed their findings by examining anonymised data held by the personal genetics and research company 23andMe, used with the donors’ consent.
The direction of effect of these 17 loci was consistently replicated in an independent sample, with 14 loci likely representing novel findings.
Some of the pinpointed genes are known to be involved in the function of synapses.
The findings suggest that broad depression is the most tractable UK Biobank phenotype for discovering genes and gene sets that further understanding of the biological pathways underlying depression.
Commenting, Dr David Howard, Postdoctoral researcher, Centre for Clinical Brain Sciences and lead author of the study, said: “This study identifies genes that potentially increase our risk of depression, adding to the evidence that it is partly a genetic disorder. The findings also provide new clues to the causes of depression and we hope it will narrow down the search for therapies that could help people living with the condition.”
Depression is a leading cause of disability worldwide. Life events – such as trauma or stress – can contribute to its onset, but it is not clear why some people are more likely to develop the condition than others.
Prof Andrew McIntosh, Chair of Biological Psychiatry said: “These new findings help us better understand the causes of depression and show how the UK Biobank study and big data research has helped advance mental health research. We hope that the UK’s growing health data research capacity will help us to make major advances in our understanding of depression in coming years.”
The study was published in Nature Communications.
Antidepressants more effective in treating depression than placebo, largest ever meta-analysis finds
A major meta-analysis comparing 21 commonly used antidepressants concludes that all are more effective than placebo for the short-term treatment of acute depression in adults, with effectiveness ranging from small to moderate for different drugs.
The international study, published in The Lancet earlier this year, is a network meta-analysis of 522 double-blind, randomised controlled trials (RCTs) comprising a total of 116,477 participants. The study includes the largest amount of unpublished data to date, and all the data from the study have been made freely available online.
Because of inadequate resources, antidepressants are used more frequently than psychological interventions. However, there is considerable debate about their effectiveness. As part of the study, the authors identified all double-blind RCTs comparing antidepressants with placebo, or with another antidepressants (head-to-head trials) for the acute treatment (over eight weeks) of major depression in adults aged 18 years or more.
The authors then contacted pharmaceutical companies, original study authors and regulatory agencies to supplement incomplete reports of the original papers, or provide data for unpublished studies.
The primary outcomes were efficacy (ie, the amount of people who had a reduction in depressive symptoms of 50 per cent or more on a validated rating scale over eight weeks) and acceptability (proportion of patients who withdrew from the study for any reason by week eight).
Overall, 522 double-blind RCTs carried out between 1979 and 2016 comparing 21 commonly used antidepressants or placebo were included in the meta-analysis, the largest ever in psychiatry.
A total of 87,052 participants had been randomly assigned to receive a drug and 29,425 to receive placebo. The majority of patients had moderate-to-severe depression.
The meta-analysis found that all 21 antidepressants were more effective than placebo and only one drug (clomipramine) less acceptable than placebo.
Some antidepressants were found to be more effective than others, with agomelatine, amitriptyline, escitalopram, mirtazapine, paroxetine, venlafaxine, and vortioxetine proving most effective, and fluoxetine, fluvoxamine, reboxetine, and trazodone being the least effective.
The majority of the most effective antidepressants are now off patent and available in generic form.
Antidepressants also differed in terms of acceptability, with agomelatine, citalopram, escitalopram, fluoxetine, sertraline, and vortioxetine proving most tolerable, and amitriptyline, clomipramine, duloxetine, fluvoxamine, reboxetine, trazodone, and venlafaxine being the least tolerable, according to the studies analysed.
The authors note that the data included in the meta-analysis may not necessarily apply to longer-term antidepressant use.
The differences in efficacy and acceptability between different antidepressants were smaller when data from placebo-controlled trials were also considered.
In order to ensure that the trials included in the meta-analysis were comparable, the authors excluded studies with patients who also had bipolar depression, symptoms of psychosis or treatment-resistant depression, meaning that the findings may not apply to these patients.
“Our study brings together the best available evidence to inform and guide doctors and patients in their treatment decisions,” said Dr Andrea Cipriani of Oxford University’s Department of Psychiatry.
“We found that the most commonly used antidepressants are more effective than placebo, with some more effective than others. Our findings are relevant for adults experiencing a first or second episode of depression – the typical population seen in general practice.
“Antidepressants can be an effective tool to treat major depression, but this does not necessarily mean that antidepressants should always be the first-line of treatment. Medication should always be considered alongside other options, such as psychological therapies, where these are available. Patients should be aware of the potential benefits from antidepressants and always speak to the doctors about the most suitable treatment for them individually.”
The majority – 409 (78 per cent) – of the 522 trials were funded by pharmaceutical companies and the authors retrieved unpublished information for 274 (52 per cent) of the trials included in the meta-analysis.
Antidepressants may be useful in HIV patients experiencing depression
A new Cochrane review study has found that antidepressant therapy may be more beneficial than placebo for the treatment of depression in people living with HIV.
The researchers assessed randomised controlled trials that compared antidepressant drugs to placebo or other treatment of depression in people living with HIV.
All the 10 studies (total 709 participants) included in the review were conducted between 1 January 1980 and 18 April 2017.
Most studies were conducted more than a decade ago, in the US, in men predominantly.
The review found that antidepressant therapy may improve depressive symptoms when compared to a placebo tablet.
There was no clear evidence of a difference in the number of people who dropped out of care when comparing people who received antidepressants with people who received a placebo.
They review authors said they could not be certain if one type of antidepressant works better than another.
Side effects were very common among all study participants. Although there were no clear conclusions on which side effects were most common or if side effects occurred more frequently in people taking antidepressants compared to a placebo, participants receiving selective serotonin reuptake inhibitors (SSRIs) did report sexual problems frequently. People receiving tricyclic antidepressants reported constipation and dry mouth frequently.
No studies reported on how antidepressant therapy affected the effectiveness of antiretroviral therapy.
The low quality of the evidence contributing to this assessment and the lack of studies representing people living with HIV from generalised epidemics in low- to middle-income countries make the relevance of these finding in today’s context limited, noted the review authors.
They recommend that new studies on treatment of depression should be conducted in countries and population groups where HIV is most common. These studies should evaluate what causes depression in these populations and how to best to incorporate antidepressant therapy with other strategies for the management of this depression.
Such studies should incorporate evaluation of stepped care models and health system strengthening interventions in the study design. In addition, outcomes related to HIV care and antiretroviral therapy should be reported, the review concludes.